FEPA News

FEPA NEWS 45 50 Developments in Philately With this experiment, the brown colouration of the red Orient Express vignette appeared after a time and was due to the formation of lead sulphide through the following reaction: Pb2+ + S2- � PbS (brown). Fig. 6: Comparison of an Orient Express vignette discoloured brown by lead sulphide in the above experiment with an (original) red vignette. 4 Discussion of the results Through the use of X-ray fluorescence spectroscopy, the authors were able to show that the colour of the red Orient Express vignettes is due to red lead (also known as Parisian red) and thus lead (II, IV) oxide, which was a typical and frequently used dye at that time. The variation in the intensity of the spectra was to be expected in view of the inhomogeneous colour distribution. The authors were, therefore, also able to contribute to colour determination in philately through spectroscopic means. They are convinced that spectroscopic methods will increasingly be used in the future, ultimately leading to more reliability for the collector as regards colour determination. It was demonstrated that lead in oxidation stage II (Pb2+) reacts with hydrogen sulphide to give lead sulphide, which results in a brown discolouration of the red Orient Express vignette. From this the authors conclude that the colour of the brown Orient Express vignettes is explained by environmental influences. Therefore, the authors also present the theory that the colour of the brown Orient Express vignettes is not a colour in its own right but merely results from the formation of lead sulphide. The examination presented here, with its results, is consistent with discussions held for years concerning lead sulphide damage to classic stamps. 5. Literature [1] G. Herzberg, Atomic Spectra and Atomic Structure, Dover Press New York, Reprint 1990 [2] Dr. U. Ferchenbauer, Österreich 1850-1918, Band IV, Vienna 2008 [3] Ute Dorr (FRPSL), Elmar Dorr (FRPSL), Der Orientexpress 1883–1914, September 2019 [4] Wolfgang Maassen (FRPSL), Wider die Zerstörung in der Philatelie. Zur Aufbewahrung und Bewahrung philatelistischer Schätze, Band 12 der Reihe „Ratgeber für Briefmarkensammler“, Schwalmtal 2016 [5] Udo Groß, Fahndung nach Bleichromat, DBZ, 3/2019 Acknowledgement The authors express also their thanks for the support provided by: © Helmut Fischer GmbH, Institut für Elektronik und Messtechnik, Sindelfingen/Germany